A Optical Surface Imaging System (CatalystHD) For Patient Positioning In Radiotherapy

Background:The Optical Surface imaging System(OSIS)is a simple,fast,reproducible,and accurate solution for patient set up and can minimize random day-to-day set up errors.Conebeam computed tomography(CBCT)has been wide-1y adopt ed and provides the most accurate patient positioning with a relatively low extra imaging dose to the patient?Purpose:We investigated the performance of the CatalystHD system compared to the gold standard CBCT in a clinical routine environment for a variety of tumor sites.Material and methods.Displacements from concurrent OSIS and CBCT registrations were compared in a total of 770 setups of 67 patients to analyze the interfractional displacement and positioning displacement in four dimensions(lateral,longitudinal,and vertical directions,rot degree).Results.The interfractional displacement on the lateral,longitudinal,vertical directions and rot degree for OSIS was-0.22(± 1.88)mm?-0.15(± 1.63)mm?-0.04(± 1.23)mm? 0.15(±0.75)°for head and neck region,0.04(±2.23)mm?0.26(±3.75)mm?-0.30(±1.78)mm ? 0.17(±0.86)°for abdomen,-0.06(±2.19)mm?0.21(±3.58)mm?-0.27(± 1.73)mm ? 0.17(±0.85)°for all?ThedurationforCBCTscanwasabout60seconds(s),while that for image processing,matching,and couch displacement was at least 5 minutes(min).The average scanning time with OSIS was less than 30s,and the total duration for positioning was less than lmin.Conclusion.OSIS is an efficient tool to improve the accuracy and increase the speed for verifying the patient positioning in radiotherapy.